Improvement in files



UNITED STATES Pn'rn WILLIAM MILLSPAUGH, OF MIDDLETOWN, NEW YORK.

lM PROVEMENT IN FILES.

Specification forming part of Letters Patent No. 210,799, dated December10, 1878; application filed I September 3, 1878.

To all whom it may concern:

Be it known that 1, WILLIAM MILLsPAUGH, of Middletown, in the county ofOrange and State of New York, have invented certain new and usefulImprovements in Files; and I do hereby declare that the following is afull, clear, and exact description thereof, which will enable othersskilled in the art to which it appertains to make and use the same,reference being had to the accompanying drawings, and to the letters ofreference marked thereon, which form a part of this specification.

The nature of my invention consists in providing a file with a hole oropening through its heel, for the purpose of preventing the file fromcracking while being tempered, as will be hereinafter more fully setforth.

In the annexed drawing, to which reference is made, Figure 1 is aperspective view of a file embodying my invention. Fig. 2 is alongitudinal section of the same.

It is well known by manufacturers of files that in the very last stageof making filesnamely, in the tempering of the same-a comparativelygreat number of them crack at the heel, thus causing considerable loss,not only in material, but also in the time and labor already expended onsuch files. The reason that files crack at this point is on account ofthe unequal contraction and expansion. When the end of the file-blank isheated for the purpose of forging the tang it is heated down a suitabledistance for that purpose, the rest of the blank, of course, remainingcold: Then when the file is heated for hardening purposes the reverseend of the file is heated up to the point that the file had previouslybeen heated for forging the tang. One end is heated in a coal-fire forforging, and the reverse end heated up to the same point in a liquidbath, hence the unequal condition or nature of the steel; and whenplunged into the hardeningbath the file is very hot up to within an inchof the shoulder, and the balance of the file comparatively cool. Thisoften causes the file to crack, such crack, as a rule, starting from thelast tooth or last out made.

Files cannot well be, and are never, heated uniformly the whole length,as the temperer has to use tongs to place them in the bath, and has tofrequently remove them from the bath to note the color or degree ofheat; hence the heel does not come in contact with the liquid.

To obviate this difficulty of cracking is the object of my invention;and to this end I make in the heel B of the file A a hole or opening, a,of any suitable size and shape, this opening extending into the file toa point beyond where the file is cut.

This opening compensates for the unequal contraction and expansion, soas to prevent cracking; and with such opening, even should the filecrack from one edge, the crack will only extend to the opening, leavingthe other side perfectly faultless; and the file, notwithstanding thecrack on one side, will be sufficiently strong and durable for allpractical purposes.

Having thus fully described my invention, what I claim. as new, anddesire to secure by Letters Patent, is-

In a file, the heel formed with opening a, extending into the filebeyond where the file is cut, and the outer edges of the heel solid orintact, whereby the contraction and expansion in tempering are providedfor to prevent cracking, and in any event to prevent cracking entirelyacross the heel of the file, substantially as and for the purpose setforth.

In testimony that I claim the foregoing as my own I have hereto affixedmy signature in presence of two witnesses.

Vi/M. M ILLSPAUGH.

Witnesses FRANK GALT, O. L. Evnnrr.

G. R. NEBINGER.

Churn.

No. 210,800. Patented Dec. 10,1878.

@itmsszs ATTORNEY.

N. PETERS, PHOTO-UTNQGRAPMER. WasnmGToN. D c.

